I came to this question few years ago and had done some further study on them.......We need to use the Appendix C - d2 table for K constants calculation.

K1 - Used for Repeatability, Equipment Variation (EV) calculation

Find the d2 from Appendix C - d2 table,

focus on the subgroup size(m) for

__number of trials __we used in GR&R study, number of subgroups (g) for

__parts x number of operators __we used in GR&R study. If the parts x number of operator greater then 20, find the d2 at the bottom of the table.

K1 = 1/d2

K2 - Used for Reproducibility, Appraiser Variation (AV) calculation

Find the d2 from Appendix C - d2 table,

focus on the subgroup size(m) for

__number of operators __we used in GR&R study, number of subgroups (g) is set as 1 as there is only one range calculation in this study.

K2 = 1/d2

K3 - Used for Part Variation (PV) calculation

Find the d2 from Appendix C - d2 table,

focus on the subgroup size(m) for

__number of samples __we used in GR&R study, number of subgroups (g) is set as 1 as there is only one range calculation in this study.

K3 = 1/d2

AIAG MSA guideline used formula K = 1/d2, all the sigma (EV, AV and PV) calculated used the original formula with K value replaced and %PT Ratio = (100x 5.15 x sigma R&R)/product specification.

Larry B. Barrentine used formula K = 5.15/d2, all the sigma (EV, AV and PV) calculated used the original formula with K value replaced

__BUT divided by 5.15 back__and %PT Ratio = (100 x 5.15 x sigma R&R)/product specification.

Noted: We do not use the factor 5.15 or 6 in GR&R% calculation (compare to process variation), it is only apply in PT Ratio calculation (compare to product specification)